Application Of Typical Metal Oxide Composites In Electrochemical Detection Of Heavy Metal Ions

With the development of society and economy,environmental pollution is becoming more and more serious.Among them,heavy metal pollution in water has become a worldwide pollution problem,which seriously threatens human health.Real-time,fast and accurate detection of heavy metal ions in water has become an urgent problem in the world.Therefore,there is great significance to achieve high sensitivity,low detection limit,high selectivity detection of heavy metals in water,as well as correcty evaluate water environmental pollution status and prediction of heavy metal content in drinking water.In the detection technology of heavy metal ions,electrochemical detection methods stand out because of its fast,accurate,real-time,anti-interference and other characteristics.Metal oxides are a kind of nanomaterials with low toxicity,high catalytic activity and high conductivity,which attract electrochemical researchers to apply them in the construction of electrochemical sensors.The metal oxide composites synthesized by composite and surface modification not only maintain the original good biocompatibility,but also increase their specific surface area and electrochemical active sites.In this paper,a series of metal oxide composites were synthesized based on metal oxides,and their applications in electrochemical detection of heavy metal ions were discussed.1.Electrochemical sensors based on Fe₃O₄@PANI nanocomposites for sensitive detection of Pb²⁺In this work,an easy-to-use electrochemical sensor has been developed for the quantitative detection of Pb²⁺.Core-shell ferric oxide@polyaniline?Fe₃O₄@PANI?nanoparticles were used as electrode materials to modify glassy carbon electrodes as platforms for detecting Pb²⁺.Fe₃O₄ nanospheres have large specific surface area and provide more binding sites for heavy metals adsorption and enrichment.PANI,as a conductive polymer with excellent electronic conductivity,contains a large number of amino and imino on its surface.It can not only improve the electron transmission speed in the detection process,but also produce good chelating effect with lead,thus improving the detection sensitivity.Under the optimum experimental conditions,the detection limit of the sensor is 0.03 nmol·L^-1,and the detection range is 0.1-1.0×10⁴ nmol·L^-1.At the same time,the sensor constructed by Fe₃O₄@PANI operate easy and fast.It performs well in stability,reproducibility and ionic interference.The sensor has achieved satisfactory results in the detection of actual water samples,and has promising application value in the detection of actual samples.2.Constructing an electrochemical sensor based on RGO/Co₃O₄ for quantitative detection of Cu²⁺Multistage porous RGO/Co₃O₄ was synthesized by coprecipitation and used as electrode material to modify glassy carbon electrode.An electrochemical sensor was constructed for the quantitative determination of Cu²⁺in water samples.In this work,when graphene oxide is reduced,Co₃O₄ precipitates on reduced graphene oxide,forming multilayer porous morphology of RGO/Co₃O₄,which not only solves the problem of easy agglomeration for Co₃O₄ because of small size,but also makes RGO/Co₃O₄ have larger specific surface area and larger conductivity,thus showing better electrochemical performance.Under the optimum experimental conditions,the detection limit of the designed sensor for Cu²⁺is 0.3 nmol·L^-1,and the detection range is 1 nmol·L^-1 to 1?mol·L^-1.It shows good stability,reproducibility and ion interference,and has a certain application prospects in practical applications.3.Electrochemical sensors based on RGO/SnO₂/Au NPs composites for sensitive detection of Pb²⁺An electrochemical sensor based on RGO/SnO₂/Au NPs composite material was constructed for the sensitive detection of heavy metal ions for the first time.Graphene oxide was synthesized by modified Hummer's method.The large specific surface area of graphene oxide provided more groups for SnO₂ and Au NPs fixation.SnO₂ and Au NPs were synthesized on the surface while graphene oxide was reduced by the reducibility of stannous oxide.SnO₂ nanoparticles have high conductivity,and Au NPs can capture more metal ions.RGO/SnO₂/Au NPs composites are sensitive to Pb²⁺in water samples by adsorption and chelation of heavy metal ions.Under the optimum conditions,RGO/SnO₂/Au NPs sensor showed a lower detection limit for Pb²⁺.The prepared heavy metal sensor has excellent stability,reproducibility and ion interference,and has practical value.